A decrease in the performance of a refrigeration unit often confuses owners of household appliances, forcing them to call a technician or even think about buying a new device. However, in many cases, the problem lies in a banal blockage of the unit that circulates the refrigerant, and you can solve it yourself with a minimum set of tools. Understanding the principle of operation capillary system allows you to effectively diagnose a malfunction and eliminate ice jams or debris blockages without expensive intervention from a service center.
The capillary tube is a thin copper coil that serves as a choke, creating a pressure difference between the condenser and evaporator. It is thanks to this element that freon transitions from liquid to gaseous state, actively absorbing heat from the refrigerator chambers. When this thin channel with a diameter of less than a millimeter becomes clogged, circulation stops, the compressor begins to idle or overheat, and the cooling inside the refrigeration chamber stops.
Before taking active steps, you must clearly understand the risks associated with violating the tightness of the system. Any mistake when working with copper pipes can lead to a gas leak or moisture ingress, which will require a complete recharge of the unit. In this article, we will analyze proven cleaning methods that will help restore the performance of your The principle of operation and symptoms of a clogged capillary refrigerator
Operating principle and symptoms of capillary blockage
To effectively eliminate the malfunction, it is important to understand the physics of the process. In good condition, the high-pressure refrigerant flows from the condenser into the capillary, where its speed increases sharply and the pressure drops. This causes sudden cooling and partial evaporation of freon before entering the evaporator. If the system appears hydraulic resistancein excess of the calculated value, the entire cycle is disrupted.
The main symptom of the problem is the inability of the refrigerator to reach the set temperature even with continuous operation of the compressor. You may notice that the condenser (grid at the back) is warm only at the very beginning or, conversely, cold, and the motor-compressor itself operates with a characteristic hum or periodically clicks, trying to start. In some cases, a bulge forms on the tube before entering the evaporator or, conversely, it becomes cold along its entire length, which indicates a place where the flow is blocked.
Often the blockage is accompanied by the formation of a so-called “ice plug”. This happens when there is moisture in the system, which, when leaving the capillary and a sharp drop in pressure, freezes, blocking the passage. You can distinguish a mechanical blockage from an ice plug by observing the behavior of the unit after defrosting: if, after a long shutdown, the refrigerator begins to work normally for a couple of hours, and then stops cooling again - the problem is precisely moisture in the system.
Necessary tools and safety measures
Repairing the refrigeration circuit requires a specific set tools without which high-quality cleaning is impossible. You will need a powerful soldering iron or gas torch for working with copper, as well as a set of pipe cutters and flaring tools. It is critically important to have a hand-held vacuum pump or compressor on hand to purge the system, since simply “blowing with your mouth” the capillary will not work due to high resistance.
⚠️ Attention: Before starting any work, be sure to disconnect the refrigerator from the power supply. Working with open flames and electrical components simultaneously creates a risk of electric shock or fire.
Solder and flux will be required to seal connections. The use of acid fluxes is strictly prohibited, as their residues can corrode the copper from the inside and cause repeated blockages or leaks. It is best to use silver solder or special phosphorus-containing alloys, which provide a reliable connection without additional flux. Also be sure to prepare safety glasses and gloves to avoid burns when soldering.
☑️ Repair tools
Special attention should be paid to preparing the workplace. Ensure good ventilation of the room, as soldering may release harmful substances. If you plan to drain the remaining refrigerant (although in domestic settings this is often simply vented, which is not environmentally friendly), do this only outdoors or through a hood. Remember that some types of freons, when in contact with an open flame, can form toxic compounds.
Methods for eliminating ice blockage
Ice blockage is the most common reason for stopping circulation, caused by moisture entering the circuit. Water can enter the system due to poor-quality previous repairs, leaks or the use of substandard refrigerant. When leaving the capillary tube in a low-pressure zone, moisture freezes, forming a crystal lattice that completely blocks the passage.
The simplest, but not always effective way to combat this phenomenon is long-term defrosting. Leave the refrigerator turned off with the doors open for 24 to 48 hours. This will allow the ice inside the system to melt, and the moisture to evaporate through possible micro-gaps or be absorbed by the filter-drier, if it still retains its properties. However, this method is temporary if the source of moisture is not eliminated.
Why does the ice lock return?
The ice lock forms again if there is air with moisture left in the system or if the filter drier is completely saturated with water and can no longer absorb liquid. In such cases, it is necessary to replace the filter-drier and deep vacuum the system.
A more radical method is to flush the system with nitrogen. To do this, the circuit is depressurized, a cylinder with dry nitrogen is connected and excess pressure is created, blowing out moisture and remaining oil. Nitrogen is preferable to air, since it is absolutely dry and inert, which eliminates oxidation of the inner walls of the tubes. After purging, it is necessary to replace filter-drieras the old one will no longer be able to work effectively.
Mechanical cleaning and blowing with a compressor
If the cause of the stoppage is mechanical blockage (oxidation products, congealed oil, shavings), physical impact on the plug will be required. Craftsmen often use the backflushing method. To do this, unsolder the capillary tube from the filter drier and try to blow the system in the opposite direction using a compressor or hand pump. A pressure of several atmospheres can dislodge a stuck piece of solder or dirt.
In particularly difficult cases, when purging does not help, resort to “burning” is necessary. This method is risky and requires experience: a pump is connected to the sealed end of the capillary and pressure is created, while simultaneously heating the site of the suspected blockage with a burner. Heat causes the copper to expand and the oil to thin, which, combined with pressure, can push the plug through. However, there is a risk of burning through the thin wall of the tube, so the temperature must be controlled extremely carefully.
Sometimes a method is used using special solvents that are introduced into the system before purging. They help soften hardened oil deposits, turning them into an emulsion that is easily blown away by a stream of gas. After this procedure, the system must be thoroughly dried by vacuum to remove solvent vapors.
Replacing the filter-drier and vacuuming
Any intervention in the sealed circuit of the refrigerator, including cleaning the capillary, requires a mandatory replacement of the filter-drier. This element is a copper cylinder filled with zeolite or activated aluminum oxide, which absorbs moisture and retains mechanical impurities. An old filter that has been exposed to air for more than 15-20 minutes loses its properties and becomes a source of problems.
The replacement process is as follows: the old filter is cut off, a new one is installed in the main gap. When soldering a new filter, it is important not to overheat its body, otherwise the filler inside will lose its adsorbing properties. You only need to heat the copper fittings, quickly soldering them into the system. After installing all components, the vacuuming stage begins.
Vacuuming is a critical stage that allows you to remove air and water vapor from the system. Using a vacuum pump, a vacuum is created in the circuit, which reduces the boiling point of water, and it evaporates even at room temperature. The process should last at least 30-40 minutes until the pressure stabilizes at minimum values. This ensures that there is no moisture left in the system that can again form an ice plug.
| Work stage | Required equipment | Execution time | Criticality |
|---|---|---|---|
| Diagnostics | Thermometer, pressure gauge | 15-30 min | High |
| Removing the filter | Pipe cutter, burner | 10-15 min | Medium |
| Capillary purge | Compressor/Nitrogen | 20-40 min | High |
| Vacuuming | Vacuum pump | 40-60 min | Critical |
| Refilling with freon | Scales, cylinder with gas | 20-30 min | Critical |
Refrigerant charging and leak testing
After successful cleaning and evacuation, the final stage begins - charging the system with refrigerant. The amount of freon is strictly regulated by the manufacturer and is indicated on a sticker, usually located on the back wall or inside the chamber. The use of electronic scales when refueling is a prerequisite, since refueling "by eye" or by pressure often leads to incorrect operation of the refrigerator.
The refueling process begins with starting the compressor and supplying gas to the system through a fitting located on the suction tube. The pressure on the pressure gauge will increase, but you need to focus specifically on the mass of the filled gas. Excess refrigerant will lead to increased condensation pressure and overload of the compressor, and too little will lead to insufficient cooling and possible freezing of the evaporator.
⚠️ Attention: After refilling, be sure to check all solder joints for leaks. Use a soap solution: apply it to the seams and watch for bubbles to appear. Even a microscopic leak will eventually damage the refrigerator.
The final stage is a control run of the equipment. Turn on the refrigerator and leave it running for several hours, periodically checking the temperature in the chambers and the degree of heating of the condenser. If the unit comes into operation and turns off when the set temperature is reached, the repair can be considered successful. Otherwise, the procedure for diagnosing and searching for blockages will have to be repeated.
Prevention of repeated blockages
To avoid a recurrence of the blockage situation capillary tube, it is important to follow the operating instructions for the refrigerator. Do not allow equipment to remain idle for long periods of time in unheated rooms where temperature changes are possible, leading to moisture condensation inside the circuit. Also, try not to store products with damaged packaging, which can release aggressive fumes, corroding the copper tubes from the inside.
Regular maintenance, including cleaning the condenser from dust and checking the integrity of the seals, also indirectly affects the health of the capillary system. A clean heat exchanger ensures normal condensation pressure, preventing overheating of the oil and the formation of tarry deposits, which often cause mechanical blockages.
If you notice the first signs of deterioration in the operation of the refrigerator, do not delay diagnostics. Removing a small ice plug at an early stage will take less time and money than repairing a compressor or replacing a heat exchanger after long-term operation in emergency mode.
Is it possible to clean the capillary without disassembling the system?
It is impossible to completely clean the capillary without breaking the tightness (cutting the tube). Methods like “tapping with a hammer” or “heating with a hairdryer” may give a short-term effect, but will not eliminate the cause of the blockage. For high-quality repairs, access to the tube for connecting the equipment is necessary.
What is the danger of moisture getting into the system?
Moisture in the refrigerator system leads to the formation of ice plugs in the capillary, corrosion of the internal walls of the tubes and compressor, as well as to a chemical reaction with the oil, which results in the formation of acids that destroy the insulation of the motor windings.
Is it necessary to change the oil in the compressor when cleaning?
In most cases, during standard cleaning of the capillary, the oil is not changed, as this requires a complex flushing procedure. However, if the cause of the blockage is combustion of the compressor windings (acid breakdown), then changing the oil and flushing the system are mandatory.
How long does the capillary tube last?
The service life of the capillary tube is practically unlimited if the system is sealed and there is no moisture in it. Blockages usually occur due to external factors (poor repairs, violation of operating conditions), and not due to wear of the tube itself.